Release 1.2.1: remove clang@3.6?

[zimoun]

Hi,

The package clang-runtime@3.6.2 is broken (commit 6bed29b) and giving a
look to:

<https://data.guix.gnu.org/repository/1/branch/master/package/clang-runtime/output-history>

it seems broken since long time.  I propose to remove:

 clang
 clang-runtime
 clang-toolchain

@3.6.2.  Any objection?


Note that llvm@3.6.2 cannot be removed because of the package clamav.

Cheers,
simon